Electromagnetic energy, such as laser light, is used to perform various medical procedures including the destruction of cancerous tissues, for example. One optical device that is used in surgical tools that perform such medical procedures is a side fire optical device.
Side fire optical devices are typically used to redirect delivered electromagnetic radiation (hereinafter “laser light”) in an off-axis direction from the longitudinal axis of the delivery fiber and the device, typically at and angle of 74-76 degrees off axis. Conventional side fire optical devices operate by reflecting the electromagnetic radiation off of a beveled optical surface. The redirected output laser light is transmitted through a transmitting surface of the device to the surgical site. One exemplary side-firing optical device is disclosed in U.S. Pat. No. 5,428,699.
During surgery, components of side fire optical devices, such as the surface of the external cap, rapidly heat and cool. This thermal cycling produces large stresses in the in the components of the side fire optical device. The thermal cycling of components of the device is magnified along with the stresses in the components, when high power lasers (e.g., 100 W holmium laser energy, 120 W 532 nm laser energy, etc.) are utilized and further magnified when the device is involved in tissue contact surgery. The stresses in the side fire optical devices often cause components of the device to crack or, even worse, shatter.